Exposed-Die IC Package Interface Layer for Heat and Delamination
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Solution Overview
Problem
Integrated circuit device packages face delamination issues due to warping of package layers, which compromises the heat dissipation and mechanical integrity of the package, especially in larger formats like BGA and 3-D packages where the adhesive properties of conventional thermal interface materials are insufficient.
Innovation Solution
The introduction of an interface layer with both adhesive and thermal interface material portions, where the adhesive portions are applied above the package walls and the TIM portions are applied directly on the integrated circuit dies, providing enhanced bonding and heat dissipation, and in some cases, a flowable TIM is contained by the adhesive layer to prevent delamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a thermally-conductive interface layer is used to affix the heat spreader to the integrated circuit die, then heat dissipation is improved, but warping of the package causes delamination of the interface layer and heat spreader
Solution Approach 1:
The interface layer is segmented into two distinct functional portions: an adhesive layer portion for mechanical bonding and a thermal interface material (TIM) layer portion for heat transfer. This segmentation allows each portion to be optimized for its specific function without compromise.
Solution Approach 2:
Different portions of the interface layer have different local properties: the adhesive layer portion has high adhesion strength for bonding, while the TIM layer portion has high thermal conductivity for heat dissipation. Each portion is positioned where its specific property is most needed.
2Temperature
If conventional thermal interface materials are used in larger format packages (BGA and 3-D packages), then heat dissipation is provided, but adhesive properties are insufficient preventing delamination
Solution Approach 1:
The interface layer is divided into an adhesive layer portion and a TIM layer portion, allowing the adhesive properties to be enhanced in the adhesive layer while the TIM layer focuses on thermal conduction, resolving the insufficiency of conventional single-function TIMs in large format packages.
Solution Approach 2:
The interface layer is a composite structure combining adhesive material and thermal interface material with distinct properties. This composite approach allows simultaneous optimization of adhesive strength and thermal conductivity, which cannot be achieved with conventional single-material TIMs.
3Reliability
If the adhesive layer portion surrounds the TIM layer portion, then delamination is prevented, but the TIM must be flowable requiring containment
Solution Approach 1:
The interface layer is segmented with the adhesive layer portion forming a containment structure around the TIM layer portion. This segmentation provides both delamination prevention and flow containment for viscous TIM materials in a unified structural approach.
Solution Approach 2:
The TIM layer portion is nested within the adhesive layer portion, which acts as a containing structure. This nesting arrangement allows the adhesive layer to provide both structural bonding and containment functions while the TIM layer focuses on thermal conduction.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration significantly reduces the likelihood of delamination and enhances the mechanical stiffness and heat dissipation capabilities of the package, improving its reliability and performance by utilizing adhesive and thermal interface materials in a complementary manner.
Implementation Method 1
an interface layer including an adhesive layer portion disposed between the walls and the heat spreader to adhere the heat spreader to the walls
Implementation Method 2
a thermal interface material (TIM) layer portion coplanar with, and laterally displaced from, the adhesive layer portion, the TIM layer portion being disposed in thermally conductive relationship between the heat spreader and each respective integrated circuit die from among the at least one integrated circuit die, to dissipate heat from each respective integrated circuit die to the heat spreader
Data Source
AI summary
An integrated circuit (IC) device package includes a structure having a base and walls extending from the base, at least one IC die mounted to the base within the walls, each die having a top surface parallel to the base and having a thickness extending along an axis, perpendicular to the top surface, at most equal to a height of the walls, a thermally conductive heat spreader extending parallel to the base above the die and the walls, and an interface layer including an adhesive layer portion disposed between the walls and the heat spreader to adhere the heat spreader to the walls, and a thermal interface material (TIM) layer portion coplanar with, and laterally displaced from, the adhesive layer portion, the TIM layer portion being disposed in thermally conductive relationship between the heat spreader and each respective die, to dissipate heat from each respective die to the heat spreader.